The invention relates to an arrangement for interrupting the operation of an individual drafting frame at a spinning machine which is equipped with a plurality of identical drafting frames containing several driven bottom rollers which extend over a plurality of spinning positions or units and containing pressure rollers assigned to the individual spinning units and held by means of load carriers. The spinning units are equipped with devices for lifting the pertaining load carrier and the pressure rollers off the bottom rollers, and with devices for the clamping-in of the respective entering sliver which are controlled by monitoring devices responding to a disturbance.
Multiple arrangements are known for interrupting the operation of an individual drafting frame which are used particularly in the case of a yarn breakage. These arrangements have the advantage that, after a yarn breakage, no further fiber material will enter the drafting frame which is then sucked off as waste or may lead to the danger of a lap formation in the area of the delivery rollers. The known arrangements require a manual operation by means of which, when the respective spinning unit is restarted, the sliver must be introduced into the drafting frame. Even if the sliver still remains in the area of the feeding rollers when the operation of the drafting frame is interrupted, it is necessary, as a rule, to introduce the sliver manually into the area of the main drafting field in which double apron units and condensers or the like are arranged. In practice, it cannot be expected that, in the case of a restarting, the sliver will find the correct path by itself.
In the case of a wind-around yarn spinning machine with a high-draft drafting frame (Sussen-Parafil 2000), it is known, in the case of a yarn breakage, to clamp in the sliver in front of the drafting frame and, at the same time, move the load carrier with the pressure rollers away from the bottom rollers. In this arrangement, the sliver remains inside the drafting frame and usually extends to the pair of output rollers or the pair of delivery rollers. Also in the case of this arrangement, a manual activity is, however, required during the restarting process because, particularly in the case of extended stoppages, there is no guarantee that the sliver is still present in the area of the main drafting field and particularly in the area of the pair of delivery rollers or the pair of output rollers. This arrangement is therefore not yet completely suitable for automation.
An object of the invention is to develop an arrangement of the initially mentioned type such that the certainty of the restarting of a drafting frame is improved in such a manner that, without any manual operations, it is largely ensured that the sliver will securely and correctly enter and run between all pairs of rollers of the drafting frame.
This object is achieved by providing devices for reducing the contact of a sliver at the bottom rollers, these devices being operative when the pressure rollers are lifted off the bottom rollers.
The invention is based on the recognition that, in the case of the known arrangement, despite the lifting of the pressure rollers off the bottom rollers, the sliver could still be damaged by the fact that individual tufts or parts of the sliver, because of the contact with the driven and continuously running bottom rollers, could be torn out unintentionally so that the sliver is damaged or even destroyed completely. This danger is avoided by using preferred embodiments of the invention in that the contact between the sliver and the bottom rollers is reduced or completely eliminated. This eliminating of the contact between the sliver and the bottom rollers in connection with the clamping-in of the sliver in the feeding area has the result that, also after an extended stoppage, an undamaged sliver is present in the drafting frame so that, by the pressing-back of the load carrier into its operative position, the operation of the drafting frame can be resumed in a simple manner. The elimination or reduction of the contact between the sliver and the bottom rollers may be achieved by means of relatively simple and inexpensive devices according to especially preferred embodiments of the invention. As a result, advantages are achieved at low cost which, at best, are known in the case of drafting frames equipped with individual drives, i.e., with drives which drive one or only two spinning units. In these drafting frames, the bottom rollers can correspondingly be stopped individually. However, these drafting frames require such high expenditures that they have not found acceptance in practice.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.